(1 attachment)

The symptom is that after a swipe up/down, it sometimes looks like the progression slows down and speeds up without any further user input (beyond the gradual slow down due to "friction").
This happens on relatively complex pages more than on simple pages.
Expected result: If the content can't be scrolled at 60fps, then it should render at lower refresh rate, but the progression speed (distance/time) shouldn't be affected.
Test clip (shows visiting http://yahoo.com on both Fennec and Chrome) - notice the swipes from 00:21 to 00:26 and from 00:27 to 00:32: https://people.mozilla.org/~ahalachmi/share/content-perf/fennec-slow-fast-lowres-yahoo~2015-10-19.mp4
Chrome on android (the second half of the clip) doesn’t exhibit this behavior.
Tested using:
Fennec: Aurora 43.0a2 API11 2015-09-30
Chrome: 39.0.2171.93

(In reply to Grant from comment #3)
> Created attachment 8677980[details]
> offline version of cmxlog.zip
>
> Here is an offline copy of cmxlog you requested.
Not working for me as expected. After extracting the zip into a folder on an Android device, when I open the main page in Fennec (either while offline or while internet access is available), I don't get the mobile layout, and it doesn't really reproduce the issue while scrolling.
Did you try it and it worked for you? if yes, what are the exact steps you took to reproduce the issue with this zip?
> The online URL you can use which doesn't change is http://www.cmxlog.com/11/#
Just tried that, doesn't work for me - the page comes up quite empty and without the long list of log items, and the issue cannot be reproduced with it.
If you want to provide another attachment to reproduce it, please make sure first it works in the following scenario:
1. Disable internet access.
2. Clear the Fennec cache (settings -> privacy -> Clear now -> check only "Cache" -> Clear data)
3. open your test page in Fennec
--> The the scroll issue can be reproduced with this page.

(In reply to Kartikaya Gupta (email:kats@mozilla.com) from comment #8)
> Now that Fennec has switched to APZ, do you still see this issue?
I just tried with nightly from yesterday, and indeed I can't notice uneven progression as it was reported originally.
Can be RESOLVED-FIXED as far as I'm concerned.